Ecological dynamics

Plant tables have not been developed for this site. Until such time as they can be updated, use the plant tables in the referenced literature that correlates to this concept (refer to plant tables from legacy sites later in this section). With respect to the imperfect alignment of such correlations, be aware of these shortcomings in their applicability to conservation planning.

The Limy Escarpments ecological site is often dominated by warm-season grasses (mostly short- and mid-grasses), but also contains a mix of shrubs, forbs, succulents, and trees. New Mexico feathergrass is the one cool-season grass species that appears capable of achieving codominance here. As is typical of plant communities in this region, pronounced annual variations in precipitation translate to considerable short-term fluctuations in annual production within a given plant community phase.

There are numerous variables which affect the range of characteristics for this ecological site. Variables such as elevation, latitude, and orographic effects create a climatic gradient which influence the distribution of C3 and C4 plants. Soil properties such as surface texture, depth to and type of bedrock, parent material, and slope landform position affect the composition of plants. Natural disturbances such as drought and wildfire affect species density and cover.

The climate gradient across the CP LRU shows a greater distribution of C3 plants such as western wheatgrass and bottlebrush squirreltail where temperatures are cooler, and moisture is more abundant. Species such as hairy grama, Hall’s panicum, and yellow Indiangrass are much more common at lower elevations and more eastern longitudes.

Within this site, the dominant species of short grasses are inherently drought- and grazing-tolerant (Lauenroth, 1994). Across the western parts of the U.S., blue grama is one of the most extensively distributed grasses and occurs in a wide variety of different ecosites ranging from grasslands to shrubland and woodland sites. This grass evolved with grazing by large herbivores and, when grazed continuously, tends to form a short sod. When allowed to grow under lower grazing pressures, the plants develop the upright physiognomy of a bunchgrass. If blue grama is eliminated from an area by extended drought (3 to4 years) or disturbance such as plowing, regeneration is slow because of very slow tillering rates (Samuel, 1985), low and variable seed production, minimal seed storage in the soil (Coffin, 1989) and limited seedling germination and establishment due to particular temperature and extended soil moisture requirements for successful seedling establishment (Hyder, 1971) (Briske, 1978). Buffalograss, which is more abundant at warmer, lower elevations of this site, is often found occupying swale or depression positions across the landscape. Buffalograss is less drought-tolerant than blue grama but re-establishes more quickly following disturbance due to higher seed abundance and viability and more effective above-ground tillering (Peters, 2008).

Large-scale processes such as climate, fire and grazing influence this site. During years with favorable growing seasons, the effects of grazing may be mitigated. During years of low precipitation, grazing can magnify degradation of the site (Milchunas D.G., 1989). Fire is a natural disturbance regime that suppresses succulents and shrubs while stimulating grasses and forbs, however, in contrast to mid-grass and tall-grass prairie sites, fire is less important (Wright, 1982). This is because the drier conditions produce less vegetation/fuel load, lowering the relative fire frequency. However, historically, fires that did occur were often very expansive, especially after a series of years where above average precipitation built enough litter/fine fuels. Currently, fire suppression and more extensive grazing in the region have decreased the fire frequency, and it is unlikely that these processes could occur at a natural scale (USNVC, 2017)-G144. According to (Gebow, 2001), fire effects in the same location will vary, especially with fire timing, where seasonality can either hinder or benefit plants depending on their growing stage. Precipitation events occurring before and after fire will also influence the recovery of plants. Fire promotes rhizomatous plant species, such as western wheatgrass, that can take advantage of below-ground rhizomes from which tillering is rapidly initiated.

Grazing pressure will tend to favor grasses such as blue grama, galleta, and purple threeawn; shrubs such as broom snakeweed and prairie sagewort; and tree species such as oneseed juniper and twoneedle pinyon.

As noted in the Representative Soil Features section, there is no apparent correlation between readily-observable dynamic soil properties and ecological state on this site. Rather, the plant communities are the best indicators of an area’s position on the state and transition model.

Correlation to Legacy Information:

From the Hills (R070AY014NM) ESD – currently correlated to one of the Penrose variant components:
Historic Climax Plant Community -The site is a grassland with an aspect dominance of pinyon-juniper with an understory of grasses, forbs and browse. Approximately 50 percent of the total vegetative production are made up of grasses. Grass species are dominated by warm-season mid-grasses. Woody species make up approximately 35 percent of the vegetative production. A variety of perennial and annual forbs make up approximately 10 percent of the vegetative production. North and east facing slopes typically produce a denser vegetative cover and produce more vegetative growth than the south or west facing slopes

The following information comes from initial soil survey manuscripts that correlates to the Limy Escarpments ecological site. Note that there is not a 1:1 relationship between the Limy Escarpments site and these legacy ecological site concepts. Much of the ecological information from the manuscripts is tied to a single component rather than to entire escarpment complexes. While Shale Breaks was correlated to multiple soil series/components on escarpments, current linework suggests that initial soil surveyors had different geomorphic concepts than those applied to the Limy Escarpments site.


The Laporte component of the Limy Escarpments is currently correlated to the Loamy (R077BY033NM) site, which was designed in another MLRA. The two Penrose variant components are correlated to different sites: Hills (R070AY014NM) and Shallow Upland (R070AY003NM); it is unclear why they these components were assigned different ecological sites, as they are nearly identical. Of the three, Hills comes closest to characterizing the plants, soils, and physiography of this site. However, it doesn’t take into account the ecological differences between soils with accumulated carbonate salts in the profile from soils that do not.

From Hills (R070AY014NM) Tables
Annual production by plant type
Plant Type---------Low(Lb/Acre)---------Representative Value(Lb/Acre)---------High(Lb/Acre)
Grass/Grasslike---------212---------------------------557------------------------------------901
Shrub/Vine--------------132---------------------------347------------------------------------561
Forb-------------------------32-----------------------------84-------------------------------------136
Total-----------------------376---------------------------988------------------------------------1598

Community 1.1 plant community composition
Common Name------------Symbol--------Scientific Name-----------Annual Production (Lb/Acre)
GRASS/GRASSLIKE
1 blue grama---------------BOGR2---------Bouteloua gracilis------------------158–218
2 hairy grama---------------BOHI2---------Bouteloua hirsuta-------------------158–218
3 little bluestem-----------SCSC----------Schizachyrium scoparium-----------105–158
3 mountain muhly---------MUMO---------Muhlenbergia montana-----------32–53
4 sideoats grama-----------BOCU----------Bouteloua curtipendula------------53–105
5 big bluestem--------------ANGE---------Andropogon gerardii----------------21–53
6 common wolfstail--------LYPH----------Lycurus phleoides--------------------21–53
7 James' galleta-------------PLJA-----------Pleuraphis jamesii-------------------21–53
8 Graminoid (grass or grass-like)-2GRAM-Graminoid (grass or grass-like)---21–53
FORB
9 buckwheat-----------------ERIOG---------Eriogonum-----------------------------21–32
10 Forb, annual--------------2FA------------Forb, annual---------------------------53–105
Forb, perennial --------------2FP-------------Forb, perennial-----------------------53–105
SHRUB/VINE
11 juniper----------------------JUNIP---------Juniperus-----------------------------105–158
12 twoneedle pinyon---------PIED---------Pinus edulis---------------------------53–105
13 oak---------------------------QUERC-------Quercus-------------------------------105–158
14 hairy mountain mahogany-CEMOP-Cercocarpus montanus var. paucidentatus-53–74
15 skunkbush sumac----------RHTR---------Rhus trilobata-------------------------21–53
16 Shrub, deciduous-----------2SD----------Shrub, deciduous---------------------32–53

From the San Miguel County (NM630) manuscript:
The potential natural plant community* of the Penrose soil is mainly true mountain mahogany, blue grama, needlegrass, and little bluestem(…) As the range deteriorates, the proportion of desirable forage plants decreases and the proportion of ring muhly, galleta, pricklypear, and oneseed juniper increases. Grazing management should be designed to increase the production and reproduction of sideoats grama, western wheatgrass, and little bluestem.
*This manuscript plant information appears to fit this ecological site better than the currently correlated site. However, based on our observations, mountain mahogany does not occur on most escarpments.

Adapted from the Rangeland Productivity table in the NM630 Manuscript:
Penrose component of map unit ME (correlated here to the “Shale Breaks” range site) -- The approximate species composition of the potential plant community is as follows:
Blue Grama-----------------------------------------------30
Sideoats grama-----------------------------------------15
Needlegrass*---------------------------------------------10
Juniper------------------------------------------------------10
Little bluestem--------------------------------------------5
Indian ricegrass-------------------------------------------5
Total production in pounds per acre for unfavorable, normal, and favorable years: 400, 700, 1,000
*“Needlegrass” most likely refers to New Mexico feathergrass here.

Adapted from the Rangeland Productivity table in the NM630 Manuscript:
Mion component of map unit ME (correlated here to the “Shale Breaks” range site) -- The approximate species composition of the potential plant community is as follows:
Sideoats grama----------------------------------------20
Little bluestem-----------------------------------------20

Blue Grama----------------------------------------------20
Needleandthread*------------------------------------15
New Mexico feathergrass-------------------------10
Wolftail-----------------------------------------------------5
Red threeawn--------------------------------------------5
*Needleandthread has not been observed on the Limy Escarpments site.



From the Mora County (NM638) manuscript:
The potential natural plant community on the Mion soil component is mainly blue grama, sideoats grama, and little bluestem. The potential natural plant community of the Penrose Variant soil is mainly sideoats grama, blue grama, little bluestem, and New Mexico feathergrass. As the potential natural plant community deteriorates, little bluestem, sideoats grama, and New Mexico feathergrass decrease and there is an increase in ring muhly, threeawn, and broom snakeweed, which normally occur in small amounts in the potential natural plant community. Grazing management should be designed to increase the vigor, productivity, and reproduction of New Mexico feathergrass, little bluestem, and sideoats grama.

From the Colfax County (NM007) manuscript description of the Laporte series:
The vegetation is pinyon pine, oneseed juniper, and Gambel oak and an understory of blue grama, sideoats grama, and little bluestem.
From the Colfax County (NM007) manuscript description of the Mion series:
The vegetation is sideoats grama, fringed sagewort, yucca, pinyon pine, and one-seed juniper.